Background
For safety reasons large overhauls and remedial projects in, for example, the chemical or power generation sectors, are usually statutory in content and frequency. These cycles, beginning with ramp-down, through inspection, maintenance and ending with start-up are usually termed turnarounds or shutdowns (TARs).
Objective
The management of a TAR presents a complex planning challenge, requiring a large number of individual activities and their respective resources to be planned in such a way that the overall duration of the plant downtime is minimised as far as practicable. The high cost associated with not running often means that one is prepared to engage significant resources if it means starting up earlier.
Because a large TAR may require up to 150,000 individual activities, it becomes important to understand the trade-off between resource deployment and shutdown duration.
Existing methods
Standard software applications such as MS-Project and Primavera offer static cost and resource optimisation. TAR management requires, however, a number of dynamic variables such as available resource capacity or Repair Risk to be taken into consideration. Taking opportunities to, for example, optimise personnel deployment can reduce the time to complete a TAR or significantly increase utilisation and so minimise the opportunity cost of lost margin. Until now standard tools could not apply use data in a sufficiently flexible manner to arrive at optimal solutions, because they use classic planning routines such as PERT or CPM which are not suited to TARs.
The application of mathematics
T.A. Cook has developed a solution to the problem of TARs using “Resource-Driven-Methodology” to determine opportunities for improvement derived from a calculated cost-time curve. For each activity the model calculates the optimal resource requirement readable in the form of a compact schedule.
Using this methodology the TAR planner can enter either maximum desirable duration or required finish date. The second optimisation step creates a workable Master Plan which, taking into account the desired finish date, achieves resource levelling. The Master Plan consists of a cascaded sequence of defined activities, each with resource requirements shown using a ten column field.
The programme is set-up to allow planning data to be transferred directly from existing SAP PM/PS. The plan is then translated into a baseline MS-Project which is then optimised in a series of mathematical iterations – each of which can be downloaded into a new MS-Project plan. The preferred plan can then, in turn, be uploaded back into SAP so that the notification and capacity planning functionality (Graphical Work Order Scheduler) within SAP can be used.
Example: Resource-Levelling
In the following example – the shutdown of a vessel – it is possible to see how, using the optimisation programme, a TAR plan requiring peak manning of 180 external staff was reorganised such that it could be achieved with an average of just 50-60 staff.
In this example not only has the scheduled completion date been left unchanged but the original buffer time (due to the peak loading) has also been reduced by 23% thus leading to additional savings.
T.A. Cook is currently working with a number of clients to optimise the whole TAR process from conceptualisation to execution and review. The T.A. Cook optimisation programme provides an excellent opportunity to audit current performance and establish future improvement potential.
For more information contact:
Rupert Clark
Marketing Manager
Direct: +44 (0) 1183 260 229
Mobile: +44 (0) 7792 926 696
r.clark@tacook.com |
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